June 7, 2013

Pollution, Storms And Climate: NASA Mission Investigates How They Interact

To investigate how air pollution and natural emissions, which are pushed high into the atmosphere by large storms, affect atmospheric composition and climate, NASA´s DC-8 and ER-2 science aircraft will take flight over the southern US this summer.

This will be the most complex NASA airborne science campaign of the year drawing together coordinated observations from NASA satellites, aircraft and an array of ground sites. The project will be conducted from Houston's Ellington Field, which is operated by the agency's Johnson Space Center.

The Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign, which will involve more than 250 scientists, engineers and flight personnel, starts in August and will run through September.

The atmosphere will be probed from top to bottom by aircraft and sensors during this critical time of the year. During the late summer, weather systems are sufficiently strong and regional air pollution and natural emissions are prolific enough to pump gases and particles high into the atmosphere. There are potential global consequences for Earth´s atmosphere and climate from these elements.

"In summertime across the United States, emissions from large seasonal fires, metropolitan areas and vegetation are moved upward by thunderstorms and the North American monsoon," Brian Toon of the Department of Atmospheric and Oceanic Sciences at the University of Colorado in Boulder and SEAC4RS lead scientist said. "When these chemicals get into the stratosphere they can affect the whole Earth. They also may influence how thunderstorms behave. With SEAC4RS we hope to better understand how all these things interact."

Targeting two major regional sources of summertime emissions - intense smoke from forest fires in the US West and natural emissions of isoprene, a carbon compound, from forests in the Southeast - SEAC4RS is expected to provide new insights into the effects of the gases and tiny aerosol particles in the atmosphere.

Cloud properties can be changed by forest fire smoke as the particles can reflect and absorb incoming solar energy. This potentially produces a net cooling at the ground level and a warming of the atmosphere. Large amounts of chemicals like isoprene, added to this mixture, can alter the chemical balance of the atmosphere and damage Earth's protective ozone layer.

A number of scientific instruments in orbit, in the air and on the ground will be used to paint a detailed picture of these intertwined atmospheric processes. NASA´s A-Train, a fleet of formation flying satellites, will pass over the region every day using sensors to detect different features of the scene below. A benefit of this intense examination of the region´s atmosphere will be more accurate satellite data.

While NASA's ER-2 high-altitude aircraft flies into the stratosphere to the edge of space, NASA's DC-8 flying science laboratory will be sampling the atmosphere below it. A Learjet from SPEC Inc. of Boulder, Colorado, will measure cloud properties.

"By using aircraft to collect data from inside the atmosphere, we can compare those measurements with what our satellites see and improve the quality of the data from space," said Hal Maring of the Earth Science Division at NASA Headquarters.